body {
  background-color: #a7a3bb;
}
body .box {
  border: 1px solid #000;
  -webkit-transition: all 0.3s;
  -o-transition: all 0.3s;
  -moz-transition: all 0.3s;
  transition: all 0.3s;
}
body .img-holder {
  width: 300px;
  height: 300px;
  background: url(https://c0710.gitee.io/test/images/big-pic2.f5b36f25.png);
}

